Stallion semen quality depends on major histocompatibility complex matching to teaser mare

Jeannerat, Elise; Marti, Eliane; Berney, C; Janett, F.; Bollwein, Heinrich; Sieme, Harald; Burger, Dominik; Wedekind, Claus

doi:10.1111/mec.14490

Cited by 15 publications

(15 citation statements)

References 77 publications

(111 reference statements)

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“…In addition to delivering larger ejaculates to more elaborately ornamented females (Pizzari et al, ), male jungle fowl ( Gallus gallus ) deliver larger ejaculates to major histocompatibility complex (MHC)‐dissimilar females (Gillingham et al, ), but only dominant males regulate ejaculate volume during mating; the ejaculate of a subordinate male is constant regardless of mate quality (Pizzari et al, ). Similarly, male horses ( Equus callabus ) allocate more sperm per ejaculate to MHC‐dissimilar mares, even if exposure to the target mare is brief (Jeannerat et al, ), suggesting that males are able strategically to vary ejaculate investment according to signals of female quality, and that the expression of such signals by females would be under sexual selection.…”

Section: Postcopulatory Sexual Selection Acting On Femalesmentioning

confidence: 99%

Sexual selection and its evolutionary consequences in female animals

2018

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For sexual selection to act on a given sex, there must exist variation in the reproductive success of that sex as a result of differential access to mates or fertilisations. The mechanisms and consequences of sexual selection acting on male animals are well documented, but research on sexual selection acting on females has only recently received attention. Controversy still exists over whether sexual selection acts on females in the traditional sense, and over whether to modify the existing definition of sexual selection (to include resource competition) or to invoke alternative mechanisms (usually social selection) to explain selection acting on females in connection with reproduction. However, substantial evidence exists of females bearing characters or exhibiting behaviours that result in differential reproductive success that are analogous to those attributed to sexual selection in males. Here we summarise the literature and provide substantial evidence of female intrasexual competition for access to mates, female intersexual signalling to potential mates, and postcopulatory mechanisms such as competition between eggs for access to sperm and cryptic male allocation. Our review makes clear that sexual selection acts on females and males in similar ways but sometimes to differing extents: the ceiling for the elaboration of costly traits may be lower in females than in males. We predict that current and future research on female sexual selection will provide increasing support for the parsimony and utility of the existing definition of sexual selection.

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Section: Postcopulatory Sexual Selection Acting On Femalesmentioning

confidence: 99%

Sexual selection and its evolutionary consequences in female animals

2018

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“…The MHC types of all experimental animals were defined serologically. Equine leukocyte antigens (ELA) class I and class II were determined via microcytotoxicity tests using alloantisera detecting 26 ELA-A (MHC class I) specificities, 5 MHC class II alleles, the ELA-C allele W21, and the allele W12 (unknown MHC class) according to Lazary et al 53 and as detailed in Jeannerat et al 10 . The MHC types of the horses are shown in Supplementary Table S5.…”

Section: Mhc Determinationmentioning

confidence: 99%

“…The MHC types of the horses are shown in Supplementary Table S5. As in previous studies on horses [7][8][9][10] , a pair was classified as "MHC similar" if at least one ELA was shared between a stimulus stallion and a mare, and as "MHC dissimilar" if no ELA were shared. We decided against genotyping by MHC-linked microsatellites 54 because microsatellites are more likely to over-estimate variation in MHC structural genes than serological methods 55 .…”

Section: Mhc Determinationmentioning

confidence: 99%

Embryo survival in the oviduct not significantly influenced by major histocompatibility complex social signaling in the horse

Jeannerat

Marti

Thomas

et al. 2020

Sci Rep

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The major histocompatibility complex (MHC) influences sexual selection in various vertebrates. Recently, MHC-linked social signaling was also shown to influence female fertility in horses (Equus caballus) diagnosed 17 days after fertilization. However, it remained unclear at which stage the pregnancy was terminated. Here we test if MHC-linked cryptic female choice in horses happens during the first days of pregnancy, i.e., until shortly after embryonic entrance into the uterus and before fixation in the endometrium. We exposed estrous mares to one of several unrelated stallions, instrumentally inseminated them with semen of another stallion, and flushed the uterus 8 days later to test for the presence of embryos. In total 68 embryos could be collected from 97 experimental trials. This success rate of 70.1% was significantly different from the mean pregnancy rate of 45.7% observed 17 days after fertilization using the same experimental protocol but without embryo flushing. Embryo recovery rate was not significantly dependent on whether the mares had been socially exposed to an MHc-dissimilar or an MHc-similar stallion. these observations suggest that MHc-linked maternal strategies affect embryo survival mainly (or only) during the time of fixation in the uterus. The major histocompatibility complex (MHC) plays a key role in the adaptive immune response of vertebrates 1. MHC molecules present antigen peptides to T cells enabling the immune system to recognize pathogens 2. The MHC also influences social signaling, as demonstrated in more than 20 species so far 1,3,4. In humans, for example, at least 16 studies provide evidence for MHC-related odors or odor preference 5 , and further studies report evidence for MHC effects on mate choice or sexual responsivity in our species 6. MHC-linked social signaling is also well established in the horse (Equus caballus) 7-10. MHC-linked social signaling may not only influence kin recognition and mate choice but also maternal investment into a pregnancy 1,3,4 , either to avoid male infanticide ("Bruce effect" 11,12) or as a late form of sexual selection that favors certain MHC genotypes over others 13. In the former case, MHC-linked signals that reveal the presence of a new dominant male can induce a pregnancy block 14,15 while MHC matching between male and female would not be expected to matter 16. In the latter case, i.e. if maternal investment into a given pregnancy reveals female preferences for certain male genotypes, higher rates of failed pregnancies would be predicted for MHC-similar than for MHC-dissimilar pairs 3,4. Indeed, human couples that share MHC antigens frequently suffer from a higher prevalence of recurrent spontaneous abortions than couples that do not share MHC antigens 17,18 , and Ober et al. 19 found reduced fecundity of MHC-similar couples within Hutterites, a group of people with usually large family sizes. These MHC effects seemed not linked to inbreeding 19. Women (or females in general) are not expected to have conscious control over these physiologic...

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“…Recent analyses concluded that male and female preferences in the horse are influenced by the major histocompatibility complex (MHC; a set of genes that play a crucial role in immunity and in social signalling among vertebrates [ 47 , 48 ]): MHC-dissimilar mates are generally preferred [ 40 , 49 , 50 , 51 ]. However, when testing for MHC-dependent female preferences, Burger et al [ 50 ] could find them only during dioestrus, not during oestrus, and it remained unclear what other type of signals influenced female preferences.…”

Section: Introductionmentioning

confidence: 99%

Cycle-specific female preferences for visual and non-visual cues in the horse (Equus caballus)

et al. 2018

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Although female preferences are well studied in many mammals, the possible effects of the oestrous cycle are not yet sufficiently understood. Here we investigate female preferences for visual and non-visual male traits relative to the periodically cycling of sexual proceptivity (oestrus) and inactivity (dioestrus), respectively, in the polygynous horse (Equus caballus). We individually exposed mares to stallions in four experimental situations: (i) mares in oestrus and visual contact to stallions allowed, (ii) mares in oestrus, with blinds (wooden partitions preventing visual contact but allowing for acoustic and olfactory communication), (iii) mares in dioestrus, no blinds, and (iv) mares in dioestrus, with blinds. Contact times of the mares with each stallion, defined as the cumulative amount of time a mare was in the vicinity of an individual stallion and actively searching contact, were used to rank stallions according to each mare’s preferences. We found that preferences based on visual traits differed significantly from preferences based on non-visual traits in dioestrous mares. The mares then showed a preference for older and larger males, but only if visual cues were available. In contrast, oestrous mares showed consistent preferences with or without blinds, i.e. their preferences were mainly based on non-visual traits and could not be predicted by male age or size. Stallions who were generally preferred displayed a high libido that may have positively influenced female interest or may have been a consequence of it. We conclude that the oestrous cycle has a significant influence on female preferences for visual and non-visual male traits in the horse.

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Stallion semen quality depends on major histocompatibility complex matching to teaser mare

Cited by 15 publications

References 77 publications

Sexual selection and its evolutionary consequences in female animals

Sexual selection and its evolutionary consequences in female animals

Embryo survival in the oviduct not significantly influenced by major histocompatibility complex social signaling in the horse

Cycle-specific female preferences for visual and non-visual cues in the horse (Equus caballus)

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